Department of Psychology

Professor - Psychology & Philosophy


1. Language acquisition in children

The central organizing theme of my work is an interest in how children acquire a first language in such a short time, especially considering that the grammars of human languages are very complex and abstract achievements. For twenty years my colleague Tom Roeper and I have been obsessed with the grammar of wh-questions. We won a grant once by arguing that wh-questions were the key to understanding almost everything about the child’s grammar. They certainly have opened many avenues of exploration in our work, and we continually return to them. If you have the right kind of mind, go to wh-questions.

The range of languages being studied for acquisition purposes is ever-increasing. Even though I am virtually monolingual, through work with students and colleagues I have learned interesting things about tiny pieces of African American English, American Sign Language, Bulgarian, Dutch, French, German, Greek, Japanese, Romani, Spanish, Tibetan, Tswana, Turkish and Xhosa. I am deeply interested in universal features of language, but that involves knowing particulars!

2. Assessment of language

To determine whether a child needs special help from a therapist in learning language, it is necessary to get an accurate idea of what the child can do. How can we best assess this, especially if the child may speak a dialect that is not well represented in standard tests? Much of our recent work has been devoted to developing unbiased assessment techniques, especially for speakers of African American English ( This work has inspired efforts in other countries to seek solutions to issues of non-standard dialects there also (

In addition, we are developing a new test of Pragmatic skills for children, with a special emphasis on childrn diagnosed with autism spectrum disorders. We are conducting research with colleagues at Yale University and the Medical University of South Carolina to try out new pragmatic assessments with children and adolescents with autism who have subtle problems in these areas of language use.

3. Language and Mind

Nobody can study language without wondering about the role that language plays in human minds: does it help you think? The particular interest I have pursued is how learning complex grammar might enable the child to think in new ways about other people’s minds: to represent their beliefs, knowledge, thoughts, feelings. This area of cognitive development is called Theory of Mind, and we have asked whether language helps it develop, and if so, how? We have worked on this problem with populations of language-delayed deaf children, and are deeply interested in intervention (see below). I have several past and ongoing collaborations asking a range of questions about this. One is an NIH grant with Peter de Villiers as part of a large multi-site program project on preschool curriculum development that will follow a large cohort of children from roughly 2 to 6 years, looking at their language and theory of mind skills among other measures. (For a version of our complement comprehension test, see here: compcomp10 )

A second is a grant with Jay Garfield at Smith and others at U.Mass. exploring Tibetan - a language with special means to mark how you know what you know. This so-called “evidential” marking is a bit like tense, but marks the source of belief instead of time! How does a young child learn to mark the sources of her belief? (Visit this website for more information on the "Project on Epistemology and Indexicality in Navajo, Tibetan and English.")

4. Intervention

Researchers who have theories about how children learn encounter a new obligation as well as a testing ground for their theories: how can children who fail to learn be helped to succeed?  For several years I have assisted in the design of software for language intervention being created by Laureate Learning Systems in Winooski, Vermont, headed by Dr. Mary Sweig Wilson, a Smith alumna who was a professor of communication disorders. It is humbling to put ideas into application: how certain are we that these are the best of all possible procedures? But it is also deeply gratifying to hope that we can give children stepping stones and set them back on the right course for language acquisition. (

5. What are these people doing?

We hope working in our lab is never dull for long. We often have to create materials for children that involve acting in videos, filming strange activities and so on. Visit the photos page for some random shots of activity to make you ask: what are they up to?

Jill de Villiers


Curriculum Vitae


NIH Program Project

Lab Members